1. Field of the Invention
The present invention relates to an azimuth measuring method and an azimuth measuring apparatus which are used for measuring an azimuth of a measuring subject position from a reference position, and a position measuring method and a position measuring apparatus which are used for measuring a measuring subject position.
2. Description of the Related Art
There are examples of measuring methods for measuring slide of a slide of a slope of shoulder in a road and a hillside. In a first example, a wire is provided between a measuring subject position and a reference position, a tension meter is installed to the wire, and the occurrence of the slide of the slope is detected based on a tension of the wire. In a second example, a wire is provided between a measuring subject position and a reference position and a displacement measuring meter is installed to the wire, and the occurrence of the slide of the slope is detected based on a displacement of the wire.
According to the above-mentioned measuring methods, the measurement is performed in such a manner that a measuring system makes contact with a measuring subject. Therefore, when a distance between the measuring subject position and the reference position is increased, the wire is loosened, thus causing a measurement error. Consequently, the above measuring methods are limited to the measurement of a relatively short distance.
To overcome the above-mentioned problem, optical measuring methods are used. The optical measuring methods use optical measuring equipment such as an electro-optic distance meter, a transit, and the like. By using the optical measurement equipment, the reference position is predetermined and the measuring subject position is optically measured based on the reference position. Thus, the change in the azimuth of the measuring subject position from the reference position can be measured in a non-contact status between the measuring subject and the measuring system. Further, the distance between the measuring subject position and the reference position can be prolonged and the optical measuring methods are frequently used for the measurement of the displacement and the slide of the slope.
However, the above optical measuring equipment has a problem in that the measuring subject position cannot be directly detected and measured in underground and underwater and, therefore, the optical measuring methods cannot perform the measurement in underground and underwater.
Accordingly, it is an object of the present invention to provide a position measuring method and a position measuring apparatus in which an azimuth of a measuring subject position from a reference position can be measured even in underground and underwater.
It is another object of the present invention to provide an azimuth measuring method and an azimuth measuring apparatus in which coordinates of a measuring subject position can be measured.
It is further object of the present invention to provide a position measuring method and a position measuring apparatus in which when a measuring subject at a measuring subject position is moved at another position, the other position can be measured.
According to a first aspect of the present invention, in an azimuth measuring method, first to third exciting coils are arranged, at a reference position which is predetermined, so that central axes thereof match three perpendicular axes of a triaxial coordinate system. First to third detecting coils are arranged at a measuring subject position distant from the reference position so that central axes thereof match three perpendicular axes of a triaxial coordinate system. Voltages induced in the first to third detecting coils are sequentially measured when the first exciting coil is excited. Voltages induced in the first to third detecting coils are sequentially measured when the second exciting coil is excited. Voltages induced in the first to third detecting coils are sequentially measured when the third exciting coil is excited. An azimuth of the measuring subject position from the reference position is determined based on a predetermined calculation by using all nine induced-voltages which are obtained by the first to third detecting coils.
According to the first aspect of the present invention, an azimuth measuring apparatus comprises a signal generating circuit for outputting an AC signal, first to third exciting coils arranged, at a reference position which is predetermined, so that central axes thereof match three perpendicular axes of a triaxial coordinate system, a first switching circuit for sequentially exciting the first to third exciting coils in response to outputs of the signal generating circuit, first to third detecting coils arranged at a measuring subject position distant from the reference position so that central axes thereof match three perpendicular axes of a triaxial coordinate system, a second switching circuit for sequentially extracting outputs of the first to third exciting coils, and a voltage extracting circuit for obtaining a voltage signal from the outputs extracted by the second switching circuit. In the azimuth measuring apparatus, first, voltages induced in the first to third detecting coils are sequentially extracted when the first exciting coil is excited. Next, voltages induced in the first to third detecting coils are sequentially extracted when the second exciting coil is excited. Further, voltages induced in the first to third detecting coils are sequentially extracted when the third exciting coil is excited. An azimuth of the measuring subject position from the reference position is determined based on a predetermined calculation by using all nine induced-voltages which are obtained by the first to third detecting coils.
According to a second aspect of the present invention, an azimuth measuring apparatus comprises first to third exciting coils arranged at a reference position which is predetermined, for generating magnetic fields perpendicular to each other, a signal generating circuit for sequentially supplying AC signals to the first to third exciting coils and exciting them, first to third detecting coils arranged, at a measuring subject position distant from the reference position, so that central axes thereof match three perpendicular axes of a triaxial coordinate system, an output switching circuit for sequentially extracting outputs of the first to third detecting coils, and a voltage extracting circuit for obtaining a voltage signal from outputs extracted by the output switching circuit. In the azimuth measuring apparatus, first, voltages induced in the first to third detecting coils are sequentially extracted when the first exciting coil is excited. Next, voltages induced in the first to third detecting coils are sequentially extracted when the second exciting coil is excited. Further, voltages induced in the first to third detecting coils are sequentially extracted when the third exciting coil is excited. An azimuth of the measuring subject position from the reference position is determined based on a predetermined calculation by using all nine induced-voltages which are obtained by the first to third detecting coils. In addition, in the azimuth measuring apparatus, an output from one of the first to third exciting coils is set as a reference output of the one exciting coil. In order to generate perpendicular AC magnetic fields, when exciting one of the two remaining exciting coils excluding the one exciting coil, the signal generating circuit applies a compensating voltage to the one exciting coil and the other remaining exciting coil of the two remaining exciting coils excluding the one exciting coil so that a magnetic field output of the one of the two remaining exciting coils is perpendicular to that of the one exciting coil. When exciting the other remaining exciting coil of the two remaining exciting coils excluding the one exciting coil, the signal generating circuit applies a compensating voltage to the one exciting coil and the one of the two remaining exciting coils excluding the one exciting coil so that a magnetic field output of the other remaining exciting coil is perpendicular to magnetic field outputs of the one exciting coil and the one of the two remaining exciting coil.
According to a third aspect of the present invention, an azimuth measuring apparatus comprises first to third exciting coils arranged at a reference position which is predetermined, for generating magnetic fields perpendicular to each other, a signal generating circuit for sequentially supplying AC signals to the first to third exciting coils and exciting them, first to third detecting coils arranged, at a measuring subject position distant from the reference position, so that central axes thereof match three perpendicular axes of a triaxial coordinate system, an output switching circuit for sequentially extracting outputs of the first to third detecting coils, and a voltage extracting circuit for obtaining a voltage signal from outputs extracted by the output switching circuit. In the azimuth measuring apparatus, first, voltages induced in the first to third detecting coils are sequentially extracted when the first exciting coil is excited. Next, voltages induced in the first to third detecting coils are sequentially extracted when the second exciting coil is excited. Further, voltages induced in the first to third detecting coils are sequentially extracted when the third exciting coil is excited. An azimuth of the measuring subject position from the reference position is determined based on a predetermined calculation by using all nine induced-voltages which are obtained by the first to third detecting coils. The azimuth measuring apparatus further comprises first to third compensating coils which are wound to the central axes of the first to third exciting coils, respectively. An output from one of the first to third exciting coils is set as a reference output of the one exciting coil. In order to generate perpendicular AC magnetic fields, when exciting one of the two remaining exciting coils excluding the one exciting coil, the signal generating circuit applies a compensating voltage to one of the first to third compensating coils corresponding to the one exciting coil and one of the two remaining compensating coils, excluding the one compensating coil, corresponding to the other remaining exciting coil of the two remaining exciting coils excluding the one exciting coil, so that a magnetic field output of the one remaining exciting coil is perpendicular to that of the one exciting coil. In order to generate perpendicular AC magnetic fields, when exciting the other remaining exciting coil of the two remaining exciting coils excluding the one exciting coil, the signal generating circuit applies a compensating voltage to one of the first to third compensating coils, corresponding to the one exciting coil, and one of the two remaining compensating coils, excluding the one compensating coil, corresponding to the one remaining exciting coil of the two remaining exciting coils excluding the one exciting coil, so that a magnetic field output of the other remaining exciting coil is perpendicular to magnetic field outputs of the one exciting coil and the one remaining exciting coil.